If the bolt patterns do not match your Buick, then it would be necessary to use an adapter. But that would cause your wheels to push out further than normal. May make it look stock car like.
This is what an adapter looks like...
A simple Google search for wheel adapter will give you a couple of sites that sell them.
You need to find out your Trans Am size and your Buick size before ordering them.
Moved to Wheels and Tires section for better visibility.